Increasingly high requirements are placed on the quality of drinking water and service water. Contaminations by organic substances are increasingly being recognised as harmful to health, thereby making removal necessary. On the other hand, such substances are more and more frequently reaching the groundwater and surface water. One example of this is the increasing concentration of pharmaceutical residues in surface water.
Such contaminations are reduced using various means. One of these means is the oxidation of organic contaminations. This is particularly effectively achieved in the so-called “Advanced Oxidation Process” (AOP), in which ozone and hydrogen peroxide are introduced into the contaminated water and then react with one another to form a hydroxyl radical. This hydroxyl radical is a highly effective oxidising agent.
From the document U.S. Pat. No. 5,578,205, which is incorporated by reference, it is known to add firstly hydrogen peroxide to a flow of contaminated water and then to add ozone downstream in a single step. In this way, impurities in the treated water are at least partially broken down. The document EP 0 561 458 A1, which is incorporated by reference, describes a method for treating contaminated water in which firstly oxygen and ozone are fed at high pressure into the water in a reaction container. Hydrogen peroxide can then be added later in a separate reaction container downstream of the ozone feed point. The document EP 1 021 377 B1, which is incorporated by reference, describes a method for treating contaminated water in which ozone and hydrogen peroxide are fed directly into the main water flow and both substances are then simultaneously fully dissolved and distributed in the water in a highly effective mixing device within a few seconds. This is intended to prevent the formation of bromate. Bromate is suspected of having a carcinogenic effect. There is therefore an upper limit for the permissible bromate content in drinking water. Said method is intended to minimise the formation of bromate in the event that bromide ions exist in the water to be treated.
The document U.S. Pat. No. 7,595,003 B2, which is incorporated by reference, describes a method for disinfecting ballast water on board ships by means of ozone. In order to avoid high bromate concentrations, the concentrations of bromide and bromate are monitored and the injection of ozone is controlled according thereto.